I do not mean to come off with an edge, however, this is an article for people hiring low bid, uninsured, one man band painters out to "hustle" a buck. Hire reputable, established companies or hire someone you know or have a strong referral from. If you are arguing over watered down paint, ticky, tacky deposits, buying your own supplies, you have hired the wrong guy.
A professional painter will help you select an exterior paint designed for long-lasting results, superior protection, and ample coverage. Higher quality paint requires fewer coats and lasts far longer, saving you money down the road. Oil or latex paints in a flat/matte or satin finish make excellent choices for the exterior of your home. These paints will endure extreme weather conditions, can be customized to your specific climate, and are ideal for painting siding.
I am a painting contractor and have been since 2001. Make sure the estimate provides in writing: What is EXCLUDED as well as INCLUDED. It should state the manufacturer and type of paint going to be used. Estimate says ALL LABOR AND MATERIALS. My estimates to my customers say "guaranteed coverage" eliminates the conversations of 1 coat vs 2 coat. I have my customers submit colors 5 days prior to start date. Customers need to inform me if they are going to use pure white, dark reds, oranges, and bright yellows they need to inform me in that 5 day window, so I can adjust my pricing for 3 coats. Although this more uncommon now than years past because a lot of paint manufacturers have primer with paint products. Let the contractor know if your doing accent walls. This takes longer to cut in straight lines and it requires the contractor to purchase more paint. If you add anything on the scope of work have the painter write out the description and cost prior to them doing the work. Have the estimate say how many days it will take to perform the work. Ask how many workers will be doing the job. Make sure to enforce that number of workers their everyday until the job is complete. Do not give final payment until you do a final walk through. Walk the job when its almost complete and point out areas that you want fixed prior to the contractors final walk through. Its best to do while the workers are still in that particular area as they will have tarps down and areas covered and it will be easier for them to take care of. Purchase a roll of blue tape and stick it to areas that you want fixed. This is called a punch list.
A thorough scrubbing is a must before painting any exterior surface. It removes the dirt and broken-down paint residues that keep fresh coats from adhering and gets rid of mildew that grows on paint in all but the most arid climates. Most contractors clean with pressure washers, but in the hands of someone unfamiliar with the equipment, these can gouge wood, shatter glass, and drive water behind siding and trim. Using a hose, a pump sprayer, and a scrub brush is slower but safer, and just as effective.
If the point of hiring a well established, experienced, reputable painting contractor is to secure the professionalism and trust suggested to be inherent with that choice, then I would EXPECT that professionalism and experience to include the ability to make the proper and correct calculations for labor and materials for a fixed price quote, and there should be NO reason for the contractor to put the cost burden of their miscalculation on the consumer.
Thanks, all, for your time & efforts adding to the article & comments, especially Dave urging requesting both General Liability AND Worker Compensation insurance certificates to protect from real & fraudulent liability--from my experience especially in California, where insurance fraud is a popular income thief, even causing car collisions to collect.
Oh, where to begin? Let me start with 'watered down paint'. 25-50% before the material gets to the site? Impossible. You would basically be painting with water at that point. It would be less of a hassle, and cost, to simply use proper material. You would be forced to apply three coats instead of two, as the coverage would be horrible. Whatever cost you think might be saved in materials would be lost in labor.